linux-kernel - [PATCH 5.15 054/207] kprobes: Limit max data

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Message-Id: <20211206145612.111181799@linuxfoundation.org>
Date:   Mon,  6 Dec 2021 15:55:08 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, zhangyue <zhangyue1@...inos.cn>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 5.15 054/207] kprobes: Limit max data_size of the kretprobe instances

From: Masami Hiramatsu <mhiramat@...nel.org>

commit 6bbfa44116689469267f1a6e3d233b52114139d2 upstream.

The 'kprobe::data_size' is unsigned, thus it can not be negative.  But if
user sets it enough big number (e.g. (size_t)-8), the result of 'data_size
+ sizeof(struct kretprobe_instance)' becomes smaller than sizeof(struct
kretprobe_instance) or zero. In result, the kretprobe_instance are
allocated without enough memory, and kretprobe accesses outside of
allocated memory.

To avoid this issue, introduce a max limitation of the
kretprobe::data_size. 4KB per instance should be OK.

Link: https://lkml.kernel.org/r/163836995040.432120.10322772773821182925.stgit@devnote2

Cc: stable@...r.kernel.org
Fixes: f47cd9b553aa ("kprobes: kretprobe user entry-handler")
Reported-by: zhangyue <zhangyue1@...inos.cn>
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/linux/kprobes.h |    2 ++
 kernel/kprobes.c        |    3 +++
 2 files changed, 5 insertions(+)

--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -154,6 +154,8 @@ struct kretprobe {
 	struct kretprobe_holder *rph;
 };
 
+#define KRETPROBE_MAX_DATA_SIZE	4096
+
 struct kretprobe_instance {
 	union {
 		struct freelist_node freelist;
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2006,6 +2006,9 @@ int register_kretprobe(struct kretprobe
 		}
 	}
 
+	if (rp->data_size > KRETPROBE_MAX_DATA_SIZE)
+		return -E2BIG;
+
 	rp->kp.pre_handler = pre_handler_kretprobe;
 	rp->kp.post_handler = NULL;